1. Field of the Invention
The present invention relates to coatings as more particularly to coatings formed from zinc dialkyldithiophosphate derivatives.
2. Description of the Related Art
Surface coatings are of great importance in modern technology. The number of surface coatings applications is considerable and the demands on surface coatings continues to rise. In tribological applications, coatings are used to control friction and wear. The engine oil additive, zinc dialkyldithiophosphate (ZDDP), has been used in engine oil formulations for over 50 years due to its antiwear and antioxidant properties. ZDDP functions as an antiwear agent by forming a protective film or coating at the surfaces in sliding contact. These antiwear or tribochemical (or otherwise known as tribological) films protect the metal surfaces from excessive wear.
The present invention recognizes new applications of these ZDDP materials.
It is an object of the present invention to provide a novel coating technique.
It is another object of the present invention to provide a film formed from a ZDDP derivative material on a substrate.
Briefly stated, the invention involves a method of forming an annealed film of ZDDP derivative material on a substrate, comprising the steps of:
selecting a substrate which is reactive with ZDDP;
exposing said substrate to said atmosphere containing ZDDP for a sufficient period of time and at a sufficient temperature, so as to cause said ZDDP to thermally decompose to form a film on said substrate; and
annealing said film.
In another of its aspects, the invention provides a method of coating a substrate with a zinc dialkyldithiophosphate (ZDDP) material, comprising the steps of:
selecting a substrate which is reactive with the ZDDP material;
providing an atmosphere containing the ZDDP material at a predetermined concentration; and
exposing the substrate to the atmosphere for a sufficient period of time and at a sufficient temperature, so as to cause the ZDDP material to form a layered substrate having a layer of a ZDDP derivative material thereon; and
annealing the layered substrate.
In another of its aspects, the invention provides a substrate having a ZDDP derivative material coated thereon according to the method as defined herein above.
In still another of its aspects, the invention provides a coated material comprising a substrate having gold constituent and a surface having a ZDDP derivative material coated thereon.
In yet another aspect of the present invention, there is provided a substrate with an annealed film of ZDDP derivative material thereon.
In yet another of its aspects, there is provided a method of forming an annealed film of ZDDP derivative material on a substrate, comprising the steps of:
selecting a substrate which is reactive with ZDDP;
exposing said substrate to an oil solution containing ZDDP for a sufficient period of time and at a sufficient temperature, so as to cause said ZDDP to thermally decompose to form a film on said substrate; and
annealing said film.
In one embodiment, the oil solution includes an antioxidant.
The antioxidant, in this case, may be an aminic or a phenolic antioxidant and may, if desired, be selected from the group consisting of:
a bisphenol antioxidant or 2,5-dimercapto-1,3,4-thiadiazole derivative;
antioxidant compositions having (A) at least one secondary diarylamine, (B) at least one sulfurized olefin and/or sulfurized hindered phenol;
a phenol ashless antioxidant; or
a thiadiazole compound.